Abstract

Most assassin bugs are predators that act as important natural enemies of insect pests. Mitochondrial (mt) genomes of these insects are double-strand circular DNAs that encode 37 genes. In the present study, we explore the duplication and rearrangement of tRNA genes in the mt genome of Reduvius tenebrosus, the first mt genome from the subfamily Reduviinae. The gene order rearranges from CR (control region)-trnI-trnQ-trnM-ND2 to CR-trnQ-trnI2-trnI1-trnM-ND2. We identified 23 tRNA genes, including 22 tRNAs commonly found in insects and an additional trnI (trnI2), which has high sequence similarity to trnM. We found several pseudo genes, such as pseudo-trnI, pseudo-CR, and pseudo-ND2, in the hotspot region of gene rearrangement (between the control region and ND2). These features provided evidence that this novel gene order could be explained by the tandem duplication/random loss (TDRL) model. The tRNA duplication/anticodon mutation mechanism further explains the presence of trnI2, which is remolded from a duplicated trnM in the TDRL process (through an anticodon mutation of CAT to GAT). Our study also raises new questions as to whether the two events proceed simultaneously and if the remolded tRNA gene is fully functional. Significantly, the duplicated tRNA gene in the mitochondrial genome has evolved independently at least two times within assassin bugs.

Digital Object Identifier (DOI)

https://doi.org/10.3390/ijms17060951

Funding Information

This work was supported by grants from the National Natural Science Foundation of China (Nos. 31372229, 31420103902, and 31401991), the National Basic Research Program of China (No. 2013CB127600), the Beijing Natural Science Foundation (Nos. 6144027, 6152016), the National Key Technology R & D Program of the Ministry of Science and Technology (2012BAD19B00), the Special Fund for Scientific Research (No. 2012FY111100), and the Chinese Universities Scientific Fund (Nos. 2016QC025, 2016QC072, and 2016ZB001).